Theoretical and experimental study of foam stability mechanism by nanoparticles: Interfacial, bulk and, porous media behavior

Foam flooding has been applied as a promising method in enhanced oil recovery to obviate the challenges of gas flooding such as fingering, channeling and overriding. However, long-term foam stability is crucial for mobility control. In this work, the effective mechanisms on foam stability in the presence of CaCO3 nanoparticles were assessed both theoretically and experimentally. The static and dynamic behaviors of cationic surfactant (HTAB) foam in the presence of CaCO3 nanoparticles with different hydrophobicity were evaluated. The CaCO3 nanoparticles were treated with a series of long-chain fatty acids to generate a range of wettability. Afterward, the underlying mechanisms were revealed by conducting the supplementary experiments, including measurements of effective diffusion coefficient (Deff), Henry's constant (KH), interfacial tension (IFT), and zeta potential of nanoparticles. Further, efforts were made to analyze the interfacial interactions using xDLVO theory. By increasing of nanoparticles hydrophobicity, the continuous reduction of effective diffusion coefficient, solubility, and IFT was observed, which means higher foam stability. However, the adsorption of modified nanoparticles on the air-solution interface could reduce the total disjoining pressure between two parallel plates, supported by xDLVO prediction. This phenomenon has an adverse effect on the thin film stability. Therefore, there would be an optimum extent of nanoparticles surface modification to obtain the most stable foam stability, which was in agreement with the both bulk and porous media observations. The optimum condition was shifted to the nanoparticles modified with the lower chain fatty acids by increasing the concentration of fatty acid solutions. In this case, the negative effect of reduced disjoining pressure was more pronounced.